With the increasing demand for the use of volatile oils in the pharmaceutical and food industries, an efficient “green” extraction method for isolation of essential oils (EOs) from plant materials has become important. Solvent-free microwave extraction (SFME) is a new technique which combines microwave heating with dry distillation at atmospheric pressure for the isolation and concentration of the EOs from plant materials[1,2]. The objective of this study was to compare the SFME and conventional hydrodistillation (HD) processes for Origanum majorana L. and to characterize the resulting EO for their chemical constituents using GC/MS and antibacterial properties against a marker organisms (Table 1).
Table 1. Antimicrobial activity of Origanum majorana L. EOs. againts the bacterial strains tested by the disc diffusion method.
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a
P=Penicillin G (10 units); VA=vancomycin (30µg); AMC=amoxicillin/clavulanic acid 2:1 (30µg); CAZ=ceftazidime (30µg);
MEM=meropenem (10µg); and FEP=cefepime (30µg).
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Bacterial species
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SFME, mm
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HD, mm
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Antibiotic control, mma
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Negative contol
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S.aureus ATCC 25923
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28
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29
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35(P)
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-
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P.aeruginosa ATCC 27853
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9
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9
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27(MEM)
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-
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E.coli ATCC 25922
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29
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30
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19(AMC)
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-
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K.pneumoniae ATCC13883
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21
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21
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24(CAZ)
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-
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S.marcescens ATCC 8100
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18
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19
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32(MEM)
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-
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E.faecalis ATCC 29212
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12
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15
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21(VA)
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-
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[1] Sozmen. F, Uysal. B, Oksal. B.S, et al. (2011)J. AOAC Int., 94:243–250, [2] Uysal. B, Sozmen. F, Aktas. O, Oksal. B.S, Kose, E.O (2011) Int. J. Food Sci. Tech., 46:1455–1461
